(1) Field of Invention
The present invention relates to a high pressure, high voltage penetrator assembly, as defined in the preamble of attached claims 1 and 22. Further, the invention relates to a high pressure, high voltage penetrator for use in a penetrator unit of the assembly, as defined in the preamble of claims 14 and 17.
In order to stabilize and increase delivery of hydrocarbon process fluid, such as gas (wet gas) or liquid from a production well, whether subsea or topside, a compressor or pump is usually installed downstream of a coarse liquid separation. The compressor or pump requires a drive motor with a high power rating, usually in a current range of 500-2000 A and a voltage range of 6.6-12 kVAC. Further, in the process of transporting hydrocarbon fluids over long land based distances, flow boosters or pumps are normally required at regular intervals in order for the flow to be stable, irrespective of geographical challenges that may be encountered.
It is important to cool the drive motor, and in doing so the process fluid obtained from the production well is used as a cooling medium. In turn, this implies that the power cables to the motor as well as the penetrator assembly will be exposed to a wet fluid environment at high temperatures, typically in the range of 70° C.-200° C. and at a high pressure in the range of 100-400 bar, in particular for subsea applications.
The fluid which is used for cooling the motor is both wet, as it may contain water, and polluted, as it normally will contain electrically conductive particles and a large variety of other impurities which may lead to electrical flash-over, creep currents and voltage breakdown. In a worst scenario, such operating conditions may lead to ignition of the production gas and explosion, with catastrophic consequences.
Further, during e.g. a wet gas production, a rapid decompression may occur, and as a result devices such as O-rings and electrical insulation which have been exposed to high pressure, may simply explode, giving rise to the risk of fatal breakdown of the compressor or pump subsea installation.
In view of on one hand to require optimum withdrawal of fluid from a production well and therefore the need to increase the pressure therein to expel the fluid from the reservoir, and on the other hand the tough and hazardous environment in which a subsea compressor/pump unit has to work, with related implications if an operation failure is about to happen and is not detected in time to take counter-measures to prevent it happen, has been a headache to the profession and a challenge which has existed for years without a satisfactory solution to overcome the well known operational problems.
It has therefore been a prime object of the present invention to provide a technical solution which will remedy the deficiencies of the prior art solutions or at least reduce the operational hazards to an absolute minimum, thereby gaining operational stability, longer life of the compressor or pump and its motor, and in turn improved cost-benefit rating.